why would the fuel pump ........pump up 45 lbs. of pressure then when fuel pump starts then no pressure
Oct 8, 2010 at 1:31 PM
1996 GMC Sierra
1996 GMC SIERRA
TLTRUCK
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- 1 POST
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JDL
- ✓ASE Certified Mechanic
- 16,098 POSTS
If you have the spider fuel system, that pressure is too low. Should be 60--66 psi. With the initial prime, that is key on, no crank. The pcm will energize the fuel pump relay for a few seconds only, then if no rpm signal, the relay won't function. My info shows an oil pressure switch in parallel to the relay circuit, to the pump, on this system. Once you crank it enough to bring up oil pressure and the o/p switch closes, the pump will get voltage regardless of the relay.
Once the vehicle is running, it may function ok with less fuel pressure. The 60--66 psi was key on engine off.
Once the vehicle is running, it may function ok with less fuel pressure. The 60--66 psi was key on engine off.
Oct 8, 2010 at 2:40 PM
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